In wireless communications, different frequency bands are set aside by the Federal Communications Commission (FCC) for different purposes. Users of a particular frequency band may be primary or secondary, licensed or unlicensed users. Existing users of a particular frequency spectrum are called incumbents of that spectrum. A Cognitive Radio (CR) is typically an unlicensed secondary device that relies on dynamic spectrum access techniques to gain access to spectrum that is used by incumbents (e.g., primary licensed services). Such techniques typically require accessing a geo-location database (also referred to merely as a database) to determine available channels in the geographical area.
Incumbent transmitter parameter databases, which are often maintained by regulatory agencies such as the FCC, typically contain information about the transmission characteristics of each incumbent system and device. These characteristics include, for example, transmitter location, effective radiated power (ERP), antenna patterns, and antenna height above average terrain (HAAT), in a variety of frequency bands. One example of such a transmitter parameter database is the FCC's Consolidated Data Base System (CDBS). While these databases contain information including both signal characteristics and physical location of the incumbents, they do not contain information about secondary systems that operate opportunistically in the band (such as cognitive radios).
It is thus desirable to provide dynamic information regarding the quality and usage of available channels using detailed information about not only primary, but also secondary transmitters operating in a desired frequency band. In this manner, opportunistic secondary systems can achieve higher quality of service (e.g., higher data throughput, longer range, fewer errors) on a near real-time basis.
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